Thermally-controlled circuit interrupter



April 1 1924.

r 1,488,951 E. R. STOEKLE THERMALLY CONTROLLED CIRCUIT INTERRUPTER FiledFeb. 14 1920 INVENTOR. m :KfiAbM WWW ATTORNEY Patented Apr. 1, 1924.

UNITED STATES ERWIN R. STOEKLE, OF MILWAUKEE, WISCONSIN, ASSIGNOR TO THECUTLTIER-HAMI-v PATENT O FFICE.

HER MFG. (30., OF MILWAUKEE, WISCONSIN, A. CORPORATION' OF WISCONSIN.

THERMALLYrCONTROLLED CIRCUIT INTERRUPT'EB.

Application filed February 14, 1920. Serial No. 858,801.

To all whom. it may concern:

Be it known that I. EnwIN R. Sronxnn, a citizen of the United States,residing at Milwaukee. in the county of Milwaukee and State oflVisconsin, have invented new and useful Improvements inThermally-Controlled Circuit Interrupters, of which the following is afull. clear, concise, and exact description. reference being had to theaccompanying drawing. forming a part of this specification.

This invention relates to thermally controlled circuit interrupt-ersadapted to use in various relations.

one object of the invention is to provide a simple, etiicie'nt andreliable circuit interrupter of such character which may be used to bothbreak and re-establish .circuit withoutrenewal of parts and which may bemade to so function repeatedly without deterioration of its conductiveparts or other impairment of its etliciency.

Another object is to provide a circuit interrupter of such characterwhich may be made exceedingly sensitive and which may be calibrated andadjusted to meet widely varying conditions.

Another object is to provide a thermally controlled circuit interrupterwherein circuit is interrupted between liquid surfaces by pressure onthe liquid and in a manner to avoid the contaminating conditionsobtaining where circuit is interrupted between solid conductors or afluid and a solid conductor.

Another object is to provide a thermally :ontrolled circuit interrupterutilizing a fluid conductor which is controlled by variations in thermalconditions in such a manner as to insure quick interruption of circuitbetween the fluid surfaces. I

Another object is to provide a thermally controlled circuitinterrupterwhich may be readily designed and adjusted to re-establish circuitautomatically or to require manual resetting as may be desired.

Other objects and advantages will hereinafter appear.

According to the present invention it is proposed to employ a conductorwhich at working temperatures is in a liquid state and to utilize afluid functioning in response to thermal changes to divide such liquidconductor for interruption of circuit, such fluid preferably beingtheproduct of vaporization of a quantity of such liquid conductor.

In the accompanying drawing wherein are illustrated certain of thevarious embodiments which the invention may assume in practice,

Figure 1 is a diagrammatic illustration of a preferred construction;

Fig. 2 is a similar illustration of a slightly modified construction;while,

Fig. 3 is a similar view illustrating another slightly modifiedconstruction.

Referring to Fig. 1 of the drawing, the same illustrates an hermeticallytight c0ntainer 4 composed of insulating and heat resistive material andcomprising an enlarged bulb 5 having an axially aligned and restrictedtubular extension 6 therebelow. Electrodes 7 and 8 are sealed within theouter ends of said bulb and said extension respectively and arrangedtopenetrate material distances toward one another within the container.said electrodes being normally electrically connected by a quantity ofvaporizable liquid conductor,preferably mercury 9, filling saidextension and rising an appreciable distance within the bulb. Theremaining space within the container is preferably evacuated prior tosealing, to reduce the hydrostatic pressure upon the mercury column andalso for removal of any gaseous matter which might react unfavorablyupon the exposed conductive parts during operation. This feature,however, is not absolutely essential and on the other hand. such spacemight optionally be filled with an electrically inert and non-oxidizinggas, or might even be left open to the atmosphere. 1

Said tubular extension is provided with an interiorly enlarged portion10 to include an increased bulk of mercury, said enlarged portion beingpreferably located at. a material distance below the bulb 5. A heatingelement 11 is arranged exteriorly of the container adjacent saidincreased bulk of mercury for supplying heat thereto.

In practice heat may be supplied to the element 11 from any convenientor desired source, and upon application of a moderate degree of heatthereto the adjacent body of mercury is not. vaporized to an appreciableextent whereas any slight vaporization which may occur is counteractedby condensation within the bulb. However, upon temporary ap lica-tion ofheat above a predetermined va ue, or upon plrolonged application of alesser degree of cat, said body of mercury becomes heated to atemperature at which rapid vaporization takes place. \Vhen suchtemperature is reached, a quantity of vapor is at once formed within theenlarged portion 10 of the passage whereas the expansive force soliberated serves to displace upwardly the liquid mercury located abovethe entrapped vapor. Moreover, as such body of liquid mercury rises, thelength of its vertical component decreases very rapidly, the innerdiameter of the bulb being materially eater than that of the extension.The hyrostatic pressure upon the entrapped vapor is thus so far reducedthat the vapor pressure continues to lift the liquid mercury and finallyexpels the same from the extension. The foregoing action occurs inpractice with much rapidity and obviously results in sudden interruptionof the controlled circuit between mercury surfaces and in the absence ofair or other oxidizing agent, the sole intervening substance beingmercury vapor. And since such vapor is incapable of maintainingelectrical conductivity for moderate current and voltage values,interruption of the controlled circuit, assuming such moderate values,is accomplished without material arcing or other undesirable efi'ect,whereas for higher values the various parts may be specially designed toreduce or eliminate arcing.

Following such interruption of the controlled circuit the same mayobviously be reclosed through rc-establishment of continuity of themercury column followingreflux of mercury within the upper end of theextension 6. The inner diameter of said extension as a whole andparticularly at the junction thereof with the bulb 5 is so selected thatfollowing cooling of the entrapped vapor approximately to itscondensation temperature, the weight of the suspended mercury column issutlicient to overcome both the pressure of such vapor and the capillaryaction between the mercury and the walls of the container for causingthe mercury to flow back within the extension and reunite with thatretained in the lower portion thereof for automatic resetting of thedevice.

Fig. 2 similarly illustrates a container comprising a bulb 5 and anextension 6, the latter being arranged at an angle to the vertical andthe former being arranged with its major axis substantially horizontal,although in practice said bulb may be arranged 1n alignment with theinclined extension.

Electrodes 7 and 8 penetrate the walls 01 said container and extendappreciable distances therewithin, the electrode 7 being bent downwardlyto dip within a body 9 of mercury which normally fills the extension andthe lower portion of the bulb as in the construction aforedescribed.

In this construction, moreover, the electrodes are relatively largewhile the passage within the extension (3 is tapered and materiallycontracted near its central portion to render the ohmic resistance andconsequent heating effect of the enclosed column of mercury relativelyhigh as compared with that of said electrodes, whereby the heatdeveloped by passage through said column of an electric current inexcess of a predetermined value serves to effect vaporization, expansionand discontinuity of said column with consequent interruption of thecontrolled circuit in the manner described.

The aforedescribed inclination of the container serves to decrease thehydrostatic head upon the contracted central portion of the mercurycolumn for facilitating expulsion of the mercury constituting the upperportion of such column and also for reducing the tendency of the mercuryto flow back into the passage following such expulsion, while thejunction of said passage with the interior of the bulb is particularlydesigned to increase the capillary action tending to resist reflux ofthe mercury within said passa 'e.

uch reduction of the hydrostatic pressure and increase in capillaryaction serves to prevent automatic resetting of the device, while infurtherance of suchend the container may be indented at a point 12corresponding with the unction between the bulb and its extension, saidindentation appearing upon the inside of the container as a hump servingpartially to separate the mercury within the bulb from that within suchextension. The level of mercury within the bulb, is however, maintainedsufiiciently high to connect the two bodies of mercury on either side ofthe hump to permit circulation thereof for assisting in recondensationof any vapor liberated at moderate temperatures corresponding withnormal values of the current transmitted.

The aforedescribed parts, however. are so designed that a slightagitation of the container, following predetermined cooling of the vaporentrapped within the passage, is sufficient to effect return of liquidmercury within said passage for resetting of the device.

The construction illustrated in Fig. 3 is in most respects similar tothat last described, the electrodes and the extension being, however,designed to render the device responsive to thermal influences from anextraneous source as in 1.

In this construction, however, the containe as a whole is pivotallymounted for oscillation about a knife edge bearing 13 locatedtherebeneath in proximity to the junction of the bulb and its extension,whereby upon expulsion of mercury from the upper end of the extensionthe same flows into the bulb causing the same to overbalance the weightupon the opposite side of the knife edge, whereupon the container isadapted to tilt. bodily into the dotted line position, thus eil'ecting awide interval between the separated bodies of mercury and efl'ectivelyproviding against automatic or accidental resetting of the device.However, resetting may be readily accomplished by manual tilting of thecontainer to its full line position, whereupon the mercury is adapted toflew back into the passage for restoring the interrupted con nection.

The aforedescribed circuit interrupter may be advantageously employed innumerous relations. Thus the same, particularly as embodied in Figs. 1and 3, may be adapted to actuation through voluntary application of heatto the element 11, or the mercury column may be arranged to bemaintained at a temperature equal or proportional to that of a bodywhich is itself heated by current traversing the controlled circuit,thus adapting the device to maintain the temperature of such bodysubstantially constant. Also, said element 11 may comprise an electricheating device which may be either independent of the controlled circuitor associated therewith in any desired or preferred manner. The lattersuggested adaptation obviously includes arrangements providing overloadprotection of the controlled circuit, to which function the constructionof Fig. 2 is particularly adapted. Furthermore, each of the foregomgconstructions is capable of calibration and adjustment in numerous waysto meet widely varying demands of service, particularly through varyingthe character, size or relation of the heating element or the angle ofinclination of the container, while for particular uses the device maybe designed to provide practically any desired special characteristics.

It may be furthermore stated that the various elements aforedescribedare capable of recombination in relations other than those stated, thusfor example, either the automatically resetting type or the typerequiring voluntary resetting may optionally be rendered sensitiveeither to thermal variations produced by current of the controlledcircuit or transmitted from an extraneous source, whereas either of saidmethods of heating is equally applicable to the fixed or the oscillatingtype of container.

What I claim as new and desire to secure by Letters Patent is:

1. A thermally controlled circuit interrupter comprising a column ofconductive fluid which is liquid at working temperatures. said columnhaving associated means providing for heating the former to effectvaporization of a portion thereof, and means to restrict circulation andthereby prevent free boiling of the liquid fluid under the influence ofsaid former means to thereby provide for sudden and definiteinterruption of continuity of said column upon vaporization of saidportion thereof, said column also having associated means providing forautomatic restoration of continuity thereof following such interruption.

2. YA thermally controlled circuit interrupter comprising a column ofconductive fluidwhich is liquid at working temperatures, said columnhaving external heating means to effect vaporization of a portionthereof, and means to restrict circulation and thereby prevent freeboiling of the liquid fluid under the influence of said former means tothereby provide for sudden and definite interruption of continuity ofsaid column upon vaporization of said portion thereof.

3. A thermally controlled circuit interrupter comprising a containerhaving a tu- 'bular extension provided with an opening,

a column of conductive fluid which is liquid at working temperatures tobe contained in said extension, said column having a portion to bevaporized by local heating and a relatively constricted portion locatedbetween said former portion and said opening to provide, uponvaporization of said former portion for sudden expulsion of a portion ofsaid column from said extension and beyond said opening to therebyefl'ect sudden and wide interruption of continuity of said column.

4. A thermally controlled circuit interrupter con'iprising a containerhaving a depending tubular extension, a column of conductive fluid whichis liquid at working temperatures to be contained in said extension,said column having a portion to be vaporized and a constricted portionlocated above said former portion to provide, upon va-- porization ofsaid former portion, for sudden expulsion of the fluid locatedthereabove to thereby efl'ect sudden and wide interruption of continuityof said column.

5. A thermally controlled circuit interrupter comprising a containerhaving a depending tubular extension, a column of conductive fluid whichis liquid at working temperatures to be contained in said extension,means for subjecting a portion of said column to externally applied heatfor vaporization of such portion of the column subject to a time elementto effect expulsion of the portion of said column located above suchvaporized ortion for interruptin continuity of said column, the portion0 said column to be so heated being relatively enlarged to au ment suchtime element.

6. A therma-ly controlled circuit interrupter comprising a containerhaving an enlarged upper portion and a relatively reduced dependingtubular extension, 9. column of conductive fluid which is liquid atworking temperatures to be contained in said extension, means forsubjecting a ortion of said column to externally app ied heat forvaporization thereof subject to a time element, the portion of saidcolumn to be so heated being relatively enlarged to provide foraugmenting such time element and said column having a relativelyconstricted portion located between said enlarged portion thereof andthe enlarged portion of said container to provide upon vaporization ofsaid enlarged portion of the column, for sudden expulsion of thatportion of the column located thereabove from the extension and withinthe enlar ed portion of the container to thereby e ect sudden and wideinterruption of continuity of said column.

7. A thermally controlled circuit interrupter comprising a hermeticallytight container having an enlarged upper portion and a relativelyreduced dependin tubular extension, a column of conductive fluid whichis liquid at working temperatures to be contained in said extension,said column having a portion to be vaporized by local heating to therebyexpel a portion of said column from said extension and into the enlargedportion of said container for interruption of continuity of said column,said extension being in open communication with the interior of theenlar ed portion of the container and the parts eing proportioned toprovide for automatic reflux of liquidfluid into the extension followinggiven reduction in pressure within the extension.

8. A thermally controlled circuit interrupter comprising a hermeticallytight container having an enlarged up or portion and a relativelyreduced depen ing tubular extension, a column of conductive fluid whichis liquid at working temperatures to be contained in said extension,said column having a portion to be vaporized by local heating to therebyexpel a portion of said column from the extension and within theenlarged portion of said container for interruption of continuity ofsaid column, said extension bein in open communication with the interior0 the enlarged portion of the container and the parts being proportionedto provide for automatic reflux of liquid fluid within the extensionfollowin given reduction in pressure therewithin, t e interior of saidcontainer being substantially de-.

void of gas and non-condensing vapor to thereby prevent entrapment ofbubbles githiin said extension upon such reflux of 9. A thermallycontrolled circuit interrupter comprising a hermetically tight containerhaving an enlarged upper portion and a relatively reduced dependingtubular extension a column of conductive fluid which is liquid atworking temperatures to be contained in said extension, means for Subecting a portion of said column to externally applied heat forvaporization thereof Sub eot to a time element, the portion of saidcolumn to be so heated being relatively enlarged to provide forincreasing such time element, said column having a relativelvconstricted portion located between said etilarged portion thereof andthe enlarged portion of said container to provide, u n va orization ofsaid enlarged portion 0 the co umn, for sudden expulsion of that portionof the column located thereabove out of the extension and into theenlarged rtion of the container to thereby efl'ect su den and definiteinterruption of continuity of said column, said extension being in o 11communnication with the interior 0 the enlarged portion of the containerand the parts being proportioned to provide for reflux of the liquidfluid into the extension following given reduction in pressure as aresult of condensation or escape from such extension of the vaporizedportion of such fluid, the interior of said container beingsubstantially devoid of gas and non-condensin vapor to thereby prevententrapment of bubbles within said extension upon such reflux of fluid.

10. A thermally controlled circuit interrupter wmprising a hermeticallytight container having an enlarged u per portion and a relativelyreduced depen mg tubular extension, a column of conductive fluid whichis liquid at working temperatures to be contained in said extension,means for subjecting a portion of said column to externally applied heatfor vaporization thereof the portion of said column to be so heatedbeing relatively enlarged to provide a time element in the va rizingaction, said column having a relatively constricted rtion locatedbetween said enlarged portion thereof and the enlarged portion of saidcontainer to provide, upon vaporization of said enlarged portion of thecolumn, for sudden expulsion of that portion of the column locatedthereabove out of the extension and into the enlarged portion of thecontainer to thereby effect sudden and definite interruption ofcontinuity of said column, said extension being in open communicationwith the interior of the enlarged portion of the container, and theparts being proportioned to pro vide for delayed reflux of liquid fluidinto the extension following reduction in pressure therewithindue tocondensation or escape from such extensiorfof the vaporized portion ofsuch fluid the interior of said container being substantially devoid ofgas and non-condensing vapor to thereby prevent entrapment of bubbleswithin said extension upon such reflux of fluid.

11. A thermally controlled circuit interrupter comprising ahermetic-ally sealed container and a conducting element therein which isfluid at Working temperatures and which is subjected to thermalinfluences for vaporization to interrupt circuit therethrough and forsubsequent condensation of the vaporized portion thereof, said containerbeing substantially devoid of contained gas and non-condensing vapor andenabling reuniting of all portions of the elements separated uponcircuit interruption.

12. A thermally controlled circuit interrupter comprising a.hermetically sealed container having therein terminals to beelectrically connected and a conducting element within said container toelectrically connect said terminals, said element being fluid at workingtemperatures and subjected to thermal influences for vaporization of aportion thereof removed from both terminals to interrupt circuit betweenthe latter, said container being substantially devoid of contained gasand non-condensing vapor and enabling the element to be re-distributedfor re-establishment of circuit following condensation of the vaporizedportion of said element and recombination of the latter with theremainder of said element.

13. A thermally controlled circuit interrupter comprising a. closedcontainer having a. main chamber and a. depending tubular extension, anda conducting element which is liquid at working temperatures, saidelement extending from said main chamber into said extension and beingsubjected to thermal influences for vaporization of av portion thereofwithin said extension at a distance from said main chamber, saidextension having an internal diameter s0 restricted as to insureexpulsion therefrom of the portion of said liquid element located abovethe vapor so liberated and to resist reflux of the liquid elementtherewithin and said main chamber being materially expanded to receivethe liquid element so expelled and to reduce the hydrostatic pressureupon the entrapped vapor during such expulsion.

14. A thermally controlled circuit interrupter comprising a closedcontainer having an enlarged main chamber and a depending contractedtubular extension, a conductive element which is liquid at workingtemperatures enclosed within said container and extending from said mainchamber into said extension and external heating means for effectingvaporization of a portion of said element within said extension and at adistance from said main chamber whereby the pressure of the vapor soliberated serves to expel from said extension the portion of saidelement located above such vapor for interrupting the electricalcontinuity of said element, said extension being internally enlarged adjacentsaid heating means.

In witness whereof, I have hereunto subscribed my name.

ERWIN R. STOEKLE.

